These comments landed Collins in hot water; now his volubility may put him behind bars. On Wednesday US time Collins was charged with insider trading in relation to shares in an Australian biotechnology company.

It is alleged he tipped off his son that the firm's only drug had failed its clinical trial, allowing him and other family members to sell their stock before the share price plummeted.

The indictment has thrust Collins' seat in upstate New York to national attention, and has already lead to an influx of donations to his Democratic rival. Yet he is still favoured to win re-election in November and remain in Congress.

Representative Christopher Collins, a Republican from New York, exits federal court in New York.Credit:Bloomberg

Collins' involvement with Innate Immunotherapeutics, the obscure Australian biotech firm, dates back to 2005, seven years before he was elected to Congress. That year the company's chief executive, Simon Wilkinson, travelled to Buffalo looking for investors and met Collins, who was then a businessman.

He decided to invest and a year later became a member of the company's board. He continued to increase his stake in the Sydney-based firm, eventually holding 17 per cent of the company's stock, worth an estimated $34 million.

In 2012 Collins - running on a pro-business, small-government platform - narrowly beat a sitting Democrat to enter Congress. He had previously been a county executive, where he oversaw a massive reduction in debt.

Collins originally backed Jeb Bush in the 2016 Republican primary before switching support to Donald Trump and becoming the first sitting member of Congress to endorse him. Collins then served on Trump's transition team and has been a reliable defender of the President.

Collins was one of Donald Trump's first Congressional backers.Credit:Bloomberg

Throughout his time in Congress, Collins has also been deeply involved in health policy.

In his first House term he was asked to chair a small business subcommittee on health and technology, an appointment that complemented his biotech investment.

While serving in these roles, Collins was an evangelist for the company, a fact he acknowledged in an interview with CNN.

“I talk about it all the time, just as you would talk about your children,” he said.

At least five fellow members of Congress, including future Health and Human Services Secretary Tom Price, decided to invest in the firm. Price reportedly made more than $US225,000 on his purchase, more than tripling his initial stake.

It all came crashing down last June, when clinical trials showed the company's multiple sclerosis drug MIS416 was no more effective than a placebo. Collins recorded a paper loss of $US22 million, and there is no allegation he sold off any of his own stock.

In a letter to supporters on Wednesday, US time, said the charges against were "bad news" but maintained he and his son would be exonerated at trial. He said he would remain in Congress and stay on the ballot in November.

Even if the Republican Party wanted to remove Collins it would be extremely complicated to do so under the rules.

Collins' district, a heavily rural area near the Canadian border, has traditionally been the most conservative seat in New York state. He carried the seat at the 2016 election with 67 per cent of the vote.

Despite the whiff of impropriety surrounding Collins, the district had attracted little national attention until now. His Democrat rival Nate McMurray reported just US$81,772 cash in hand from supporters in June compared to US$1.34 million for Collins.

Following the charges, McMurray said he had doubled that total in a single day.

The Cook Political Report, a non-partisan ratings service, on Wednesday moved the seat from "solid Republican" status to "likely Republican", still a long way from a highly competitive race.

James Campbell, a political science professor at the University of Buffalo, said many Republicans would link the charges against Collins to Trump's repeated claims of bias at the FBI and Department of Justice.

"His supporters will see this as an attempt to unfairly damage him just before an election," Campbell said.

Matthew Knott is a Fairfax Media reporter based in the United States. He previously worked in the Canberra press gallery and recently finished a Masters of Journalism at Columbia University in New York.